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  • 1. Designation: A 309 – 01 Standard Test Method for Weight and Composition of Coating on Terne Sheet by the Triple-Spot Test1 This standard is issued under the fixed designation A 309; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the Department of Defense. This test method replaces Method 511.1 of Federal Test Method Standard No. 151b.1. Scope erations for Chemical Analysis of Metals, Ores, and 1.1 This test method covers the determination of the weight Related Materials3and composition of coating on terne sheet by the triple-spot E 57 Method for Chemical Analysis of White Metal Bear-method. The following three procedures are described: ing Alloys4 1.1.1 Procedure A—Stripping with sulfuric acid. E 173 Practices for Conducting Interlaboratory Studies of 1.1.2 Procedure D—Stripping with hydrochloric acid and Methods for Chemical Analysis of Metals5antimony trichloride. 3. Significance and Use 1.1.3 Procedure E—Stripping with hydrobromic acid-bromine solution. 3.1 A coating of terne metal on iron or steel articles is intended to provide drawability, solderability, or corrosion NOTE 1—Procedure B (Electrolytic Stripping) and Procedure C (Strip- resistance, or combination thereof, which can require differentping with Silver Nitrate Solution), formerly in this test method, were amounts of coating. Specifications for terne-coated sheetsdiscontinued because lack of usage. The designation for Procedure D andProcedure E are retained to avoid future confusion when reference is made frequently provide for these different classes (weights) ofonly to the procedure designation. coating so that purchasers can select that most suitable for their needs. This test method provides a means of determining the 1.2 If the percent of tin in the coating is required, stripping weight of coating for comparison with the material specifica-with hydrobromic acid-bromine is the preferred procedure. tion requirements.Steel with a predeposited electrolytic nickel coating requires atwo-stage stripping method to determine total tin content. If 4. Reagentsboth the tin and lead percentage are required, stripping with 4.1 Purity of Reagents—Reagent grade chemicals shall besulfuric acid is recommended, but caution is advised since the used in all tests. Unless otherwise indicated, it is intended thatsulfuric acid procedure has been found to produce high tin all reagents shall conform to the specifications of the Commit-results (see Section 11). tee on Analytical Reagents of the American Chemical Society, 1.3 This standard does not purport to address all of the where such specifications are available.6 Other grades may besafety concerns, if any, associated with its use. It is the used, provided it is first ascertained that the reagent is ofresponsibility of the user of this standard to establish appro- sufficiently high purity to permit its use without lessening thepriate safety and health practices and determine the applica- accuracy of the determination.bility of regulatory limitations prior to use. For specific hazardsstatements, see Section 5, Note 2, and Section 17. 5. Hazards2. Referenced Documents 5.1 For precautions to be observed in the use of certain reagents in this test method, reference shall be made to 2.1 ASTM Standards: Practices E 50. Particular precaution should be observed when A 308 Specification for Steel Sheet, Terne (Lead-Tin Alloy) Coated by the Hot-Dip Process2 E 50 Practices for Apparatus, Reagents, and Safety Consid- 3 Annual Book of ASTM Standards, Vol 03.05. 4 Discontinued; see 1985 Annual Book of ASTM Standards, Vol 03.05. 5 Discontinued; see 1996 Annual Book of ASTM Standards, Vol 03.05. 1 6 This test method is under the jurisdiction of ASTM Committee A05 on Reagent Chemicals, American Chemical Society Specifications, AmericanMetallic-Coated Iron and Steel Products and is the direct responsibility of Chemical Society, Washington, DC. For suggestions on the testing of reagents notSubcommittee A05.07 on Methods of Testing. listed by the American Chemical Society, see Analar Standards for Laboratory Current edition approved June 10, 2001. Published August 2001. Originally Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiapublished as A 309 – 47 T. Last previous edition A 309 – 94a (1999). and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, 2 Annual Book of ASTM Standards, Vol 01.06. MD.Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States. 1
  • 2. A 309 – 01using the hydrobromic acid-bromine stripping solution (Proce- 8. Procedures for Strippingdure E) as described in Section 17. 8.1 After cleaning as described in 6.3, weigh each test specimen separately to the nearest 0.001 g. Wrap a stiff6. Test Specimens platinum or nickel wire about each specimen in such a manner 6.1 Test specimens for weight of coating shall be obtained that it may be held firmly in an acid solution in a horizontalas prescribed in Specification A 308. position. Using a 600-mL beaker, heat 60 mL of H2SO4(sp gr 6.2 Specimens shall be 2.25 6 0.01 in. (57.15 6 0.25 mm) 1.84) to 250°C (Warning, see Note 3). Immerse each specimensquare or 2.54 6 0.01 in. (64.52 6 0.25 mm) in diameter, for about 11⁄2 min (see Note 4) in the hot acid; then remove andexcept that for material narrower than 2.25 in. in width, test momentarily immerse in 50 mL of distilled water contained inspecimens shall be of such a length that the area of the a 600-mL beaker. Rub the surface of the specimen with aspecimen is equal to 5.08 in.2 (3277 mm2). The weight of policeman while washing with about 50 mL of distilled watercoating in grams on a specimen 5.08 in.2 in area is numerically from a wash bottle. Dry the specimen. If the coating has notequal to the weight of coating in ounces per square foot of been completely removed, again immerse in the acid andsheet. When it is not possible to secure a specimen of 5.08 in.2 repeat the procedure. Thoroughly dry and reweigh the speci-in area, a smaller size may be used, but it is recommended that men. The loss in weight represents the weight of coatinga specimen of not less than 3 in.2 (2000 mm2) be used. together with iron dissolved from the steel sheet. NOTE 2—The area of 5.08 in.2 is achieved by a specimen 2.25 in. NOTE 3—Warning—A suitable face shield should be worn in order tosquare or having a diameter of 2.54 in. within the tolerances of the protect the operator from accidental splashing or popping of hot sulfuricprocedure. acid. 6.3 The specimens shall be clean; if necessary, they shall be NOTE 4—The stripping must be conducted in a manner to ensure thatwashed with solvent naphtha or other suitable solvent, then the temperature of the stripping solution is maintained at a minimum ofwith alcohol, and dried thoroughly. 250°C for at least 11⁄2 min after immersing the test panel. Successive strippings (at 250°C) may be necessary to remove all of the coating PROCEDURE A—STRIPPING WITH completely. SULFURIC ACID 9. Chemical Analysis7. Reagents and Materials 9.1 Cool the H2SO4 solution in which the specimen was 7.1 Hydrochloric Acid (sp gr 1.12)—Mix 500 mL of HCl stripped and combine with the washings obtained in the(sp gr 1.19) with 400 mL of distilled water. 600-mL beaker while stripping the specimen. Pour the solution 7.2 Mercuric Chloride Solution—Prepare a saturated solu- into a 500-mL volumetric flask, and rinse the beaker with HCltion of mercuric chloride (HgCl2) in water. (sp gr 1.12). Add the rinsings to the flask and dilute to the 7.3 Potassium Dichromate, Standard Solution (0.1 N, 1 mL 500-mL mark with HCl (sp gr 1.12), again diluting to the mark= 0.00559 g Fe)—Prepare and standardize as prescribed for after cooling, if necessary. (In the case of lead-coated sheets itReagent 10 in Practices E 50. may be necessary to dilute to 1 L with HCl (sp gr 1.12) to 7.4 Potassium Iodate, Standard Solution (0.05 N, 1 mL = ensure complete solution of lead, in which case appropriate0.003 g Sn)—Prepare and standardize as prescribed for Re- changes shall be made in the aliquot portions taken for theagent 12 in Practices E 50, making suitable adjustments in the subsequent tests described in 9.2, 9.3, and 9.4.) The solutionquantities of reagents and water used so that the solution will must now be analyzed for iron and, if desired, lead and tin.be 0.05 N. 9.2 Determination of Iron—Transfer a 100-mL aliquot of 7.5 Sodium Bicarbonate Solution (saturated)—Saturate the solution in the 500-mL volumetric flask (see 9.1) to afreshly boiled distilled water with NaHCO3. 400-mL beaker. Heat to boiling, rinse the cover and the sides of 7.6 Sodium Bicarbonate Solution (dilute)—Dissolve about the beaker with water, and immediately reduce the iron by the10 g of NaHCO3 in 1 L of freshly boiled distilled water. dropwise addition of the SnCl2 reducing solution. Add 3 drops 7.7 Sodium Diphenylamine Sulfonate Indicator Solution— in excess after the disappearance of the ferric iron color. CoolDissolve 0.20 g of sodium diphenylamine sulfonate in 100 mL and dilute to about 175 mL with water. Add to the solution, allof water. Store in a dark-colored bottle. at once, 10 mL of the saturated HgCl2 solution. Mix gently by 7.8 Stannous Chloride, Reducing Solution—Dissolve 100 g stirring the solution. Let stand for 3 to 5 min. Add 20 mL of theof SnCl2·2H2O in 500 mL of HCl (sp gr 1.19), dilute to 1 L, sulfuric-phosphoric acid mixture and 5 to 6 drops of theand mix. Preserve in a dark-colored bottle containing a small sodium diphenylamine sulfonate indicator solution. Titrateamount of granular or mossy tin metal. with the standard K2Cr2O7 solution to a purple end point. 7.9 Starch Solution—Prepare solution as prescribed for Calculate the grams of iron in the stripping solution as follows:Reagent 110 in Practices E 50. Iron, g 5 5 AB 7.10 Sulfuric Acid (sp gr 1.84). 7.11 Sulfuric-Phosphoric Acid Mixture— Pour 150 mL ofconcentrated sulfuric acid (H2SO4, sp gr 1.84) into 300 mL of where:water while stirring. Cool, add 150 mL of concentrated A = millilitres of K2Cr2O7 standard solution required tophosphoric acid (H3PO4, sp gr 1.69), dilute to 1 L with water, titrate to a purple end point and B = iron equivalent of the K 2Cr2O7 solution, kg/L.and mix. 2
  • 3. A 309 – 01 9.3 Determination of Tin—Transfer a 200-mL aliquot of the Weight of coating 5 A 2 Bsolution in the 500-mL volumetric flask (see 9.1) to a 300-mLErlenmeyer flask. Add 3 g of iron in the form of fine wire orthin sheet and 1 g of powdered antimony. Fit the flask with a where:one-hole rubber stopper containing a glass tube bent twice at A = loss in weight of specimen, g (see Section 8), andright angles, with the end of the short bend projecting through B = iron stripped from the test specimen (see 9.2), when athe stopper, the other end being long enough to reach almost to specimen of 5.08 in.2(3277 mm2) in area is used, g.the bottom of a beaker placed on a level with the flask. Pour For specimens of other sizes, a suitable correctionabout 300 mL of a dilute solution of NaHCO3 into this beaker. factor must be applied.Place the flask on a hot plate, with the glass tube extending into 10.2 Percent of Tin in Coating—Calculate the percent of tinthe beaker containing the dilute solution of NaHCO3. After in the coating as follows:boiling the solution in the flask for about 5 min, remove the Tin, % 5 @T/~ T 1 L!# 3 100beaker containing the dilute NaHCO 3 solution and substituteanother containing about 50 mL of a saturated solution ofNaHCO3. Move both the beaker and the flask to a cool place. where: T = tin stripped from the test specimen (see 9.3), g andThis will cause a small amount of the saturated solution of L = lead stripped from the test specimen (see 9.4), g.NaHCO 3 to enter the flask and exclude the air. Finally cool the 10.3 Percent of Lead in Coating—Calculate the percent ofsolution to about 10°C. Add 5 mL of starch solution and titrate lead in the coating by subtracting the percentage of tin fromwith KIO3 solution. It is desirable to run a duplicate analysis 100 %.for tin, adding the KIO3 solution quickly to a point slightly lessthan the end point found in the previous determination, then 11. Precision and Biasfinishing the titration more slowly. This duplicate analysis may 11.1 Due to the limited number of laboratories participatingbe run using one of the other triple-spot test specimens. in the cooperative testing of this procedure, a precisionCalculate the grams of tin stripped from the test specimen from statement conforming to the requirements of Practices E 173the number of millilitres of KIO3 solution used for the titration, cannot be furnished. Comparison of the percent tin found byas follows: the three cooperating laboratories (Table 1) with the known tin Tin, g 5 5AB/2 value in the samples indicates that the sulfuric acid procedure (Procedure A) yields high tin results. It is therefore advised that where: caution be exercised when reporting percent tin values ob- A = KIO3 solution required to titrate the samples, mL and tained using the sulfuric acid method. The weight of coating B = tin equivalent of the KIO 3 solution, kg/L. results (Table 2) generally agreed to within 0.01 oz/ft2 between 9.4 Determination of Lead—After ascertaining that all the replicate samples and between different laboratories.PbCl2 is in solution, remove a 100-mL aliquot from the500-mL volumetric flask (see 9.1) and place in a 400-mL PROCEDURE D—STRIPPING WITHbeaker. Add 10 mL of H2SO4(sp gr 1.84), cover, and evaporate HYDROCHLORIC ACID AND ANTIMONYto fumes of SO3. Cool and dilute to 200 mL with water. Allow TRICHLORIDEto settle and then filter on a weighed Gooch crucible, washing 12. Reagentwith H2SO4(1 + 19). Dry and ignite at a dull red heat. Cool andreweigh. Calculate the grams of lead stripped from the test 12.1 Antimony Trichloride-Hydrochloric Acid Solution—specimen, as follows: Dissolve approximately 40 g of SbCl3 in HCl (sp gr 1.19) and dilute to 1 L with the HCl. Lead, g 5 5~A 2 B! 3 0.6831 13. Procedure for Strippingwhere: 13.1 After cleaning as described in 6.3, weigh each testA = weight of Gooch crucible and ignited precipitate, and specimen separately to the nearest 0.001 g. Immerse in the coldB = weight of Gooch crucible. SbCl3-HCl solution until the coating is removed and all action ceases. The reaction will leave the specimen coated with10. Calculation antimony. Wash thoroughly to remove the loosely adherent 10.1 Weight of Coating—Calculate the weight of coating in antimony, dry, and reweigh. The loss in weight in grams is theounces per square foot as follows: weight of coating in ounces per square foot of sheet when a TABLE 1 Tin Determination Assumed Tin Sulfuric Acid Method (Procedure A)B Hydrobromic Acid-Bromine Method (Procedure E)B Sample ValueA Laboratory 1 Laboratory 2 Laboratory 3 Laboratory 1 Laboratory 2 Laboratory 3 A 8.6 9.9 10.2 9.2C 8.3 8.8 8.6 B 12.4 14.5 14.5 13.0C 12.2 12.7 12.2 A Values obtained using Method E 57. B All values represent an average of three determinations. C Calculated using coating weight instead of method used in 10.2. 3
  • 4. A 309 – 01 TABLE 2 Weight of Coating, oz/ft2 of Sheet Hydrochloric Acid-Antimony Trichloride Sulfuric Acid Method Hydrobromic Acid-Bromine Method Sample Method (Procedure D) (Procedure A) (Procedure E) Laboratory 1 Laboratory 2 Laboratory 3 Laboratory 1 Laboratory 2 Laboratory 3 Laboratory 1 Laboratory 2 Laboratory 3 1A 0.16 0.16 0.16 0.16 0.15 0.16 0.16 0.16 0.17 2A 0.16 0.16 0.16 0.16 0.15 0.16 0.16 0.16 0.17 1B 0.34 0.32 0.33 0.33 0.28A 0.31 0.35 0.33 0.35 2B 0.33 0.33 0.32 0.32 0.29A 0.32 0.33 0.34 0.33 A Procedural error—results not considered valid.specimen of 5.08 in.2(3277 mm2) in area is used. For speci- 16.3 Hydrobromic Acid-Bromine Stripping Solution—Mix 9mens of other sizes a suitable correction factor must be applied. volumes of hydrobromic acid (sp gr 1.49) with 1 volume of bromine liquid (Caution, see 17.2).14. Precision and Bias 16.4 Lead Solution Stock—Prepare stock lead solution by 14.1 Due to the limited number of laboratories participating dissolving 1.500 g of pure lead in 50 mL of hydrobromicin the cooperative testing of this procedure, a precision acid-bromine stripping solution (from 16.3). Dilute to 200 mLstatement conforming to the requirements of Practices E 173 in a volumetric flask with the hydrobromic acid-brominecannot be furnished. Comparison of the weight of coating stripping solution and mix (1 mL = 7.5 mg Pb).results, Table 2, indicates that generally the results agreed to 16.5 Mercuric Chloride Solution—Prepare a saturated solu-within 0.01 oz/ft2 between replicate samples and between tion of mercuric chloride (HgCl2) in water.different laboratories. 16.6 Perchloric Acid (sp gr 1.67) (Caution, see 17.3). 16.7 Potassium Dichromate, Standard Solution (0.1 N, 1PROCEDURE E—STRIPPING WITH HYDROBROMIC mL = 0.00559 g iron)—Prepare and standardize as prescribed ACID-BROMINE SOLUTION for Reagent 10 in Practices E 50.15. Apparatus and Materials 16.8 Sodium Diphenylamine Sulfonate Indicator Solution— Dissolve 0.20 g of sodium diphenylamine sulfonate in 100 mL 15.1 Atomic Absorption Spectrophotometer—The instru- of water. Store in a dark-colored bottle.ment shall consist of an atomizer and burner, suitable pressure- 16.9 Stannous Chloride, Reducing Solution—Dissolve 100regulating devices capable of maintaining constant oxidant and g of SnCl2·2H2O in 500 mL of HCl (sp gr 1.19), dilute to 1 L,fuel pressure for duration of the test, a hollow cathode lamp for and mix. Preserve in a dark-colored bottle containing a smalleach metal to be tested, an optical system capable of isolating amount of granular or mossy tin metal.the desired line of radiation, an adjustable slit, a photomulti- 16.10 Sulfuric-Phosphoric Acid Mixture— Pour 150 mL ofplier tube or other photosensitive device as a light-measuring concentrated sulfuric acid (H2SO4, sp gr 1.84) into 300 mL ofand amplifying device, and a readout device for indicating the water while stirring. Cool, add 150 mL of concentratedamount of absorbed radiation. phosphoric acid (H3PO4, sp gr 1.69), dilute to 1 L with water, 15.1.1 Hollow Cathode Lamps—A single element (tin) and mix.lamp is available and has been found satisfactory for tin 16.11 Tin Standard, Stock Solution—Prepare stock standardanalysis. solution by dissolving 1.000 g of pure tin in 100 mL of HCl 15.2 Oxidant : (1+1). Dilute to 1000 mL in a volumetric flask using HCl 15.2.1 Air—Use clean, dry air. A filter capable of removing (1+1). Concentration: 1 mL = 1000 µg tin. Commercial tinoil, water, and other foreign substances may be used. standards are available. 15.2.2 Nitrous Oxide—Laboratory and industrial high-purity grade nitrous oxide has been used satisfactorily. 17. Hazards 15.3 Fuel : 15.3.1 Acetylene—Standard, commercially available acety- 17.1 Acetylene—Warning: “Purified” grade acetylene con-lene is satisfactory (Warning, see 17.1). However, since all tains a special proprietary solvent rather than acetone, whichacetylene cylinders contain acetone, no more than three fourths can weaken the walls of poly(vinyl chloride) tubing that carriesof the volume of the tank should be used in order to prevent acetylene to the burner, causing a potentially hazardous situa-carryover of the acetone into the equipment. tion and should not be used. 15.3.2 Pressure-Reducing Valves—The supplies of fuel and 17.2 Hydrobromic Acid-Bromine Solution:oxidant shall be maintained at pressures somewhat higher than 17.2.1 The handling of bromine, either as a liquid or in thethe controlled operating pressure of the instrument by means of vapor form, is a health hazard. Therefore, the followingsuitable pressure-reducing valves. minimum precautions should be taken: 17.2.2 Extreme care should be taken to avoid inhaling the16. Reagents corrosive fumes: conduct all mixing, stripping, and evaporating 16.1 Hydrochloric Acid (1+1)—Mix 1 volume of concen- operations in a well-ventilated hood.trated hydrochloric acid (sp gr 1.19) with 1 volume of water. 17.2.3 Avoid skin contact with the liquid or fumes: rubber 16.2 Hydrochloric Acid (1+20)—Mix 1 volume of concen- gloves may be worn as protection from accidental spillage ortrated hydrochloric acid (sp gr 1.19) with 20 volumes of water. splashes. 4
  • 5. A 309 – 01 17.2.4 If liquid should come into contact with bare skin, 19.3.1 Terne-Coated Sheet Without Predeposited Electro-immediately wash the affected area thoroughly with water. lytic Nickel Coating—Use Procedure E.Medical attention may be necessary if burns are severe. 19.3.2 Terne-Coated Sheet With Predeposited Electrolytic 17.2.5 Before disposal, neutralize all bromine-containing Nickel Coating:solutions using a 10 % solution of sodium thiosulfate (Na2S 19.3.2.1 Use a combination of Procedure E (to strip coating2O3). Add thiosulfate solution and stir until the bromine color overlay) and an additional alloy layer stripping procedure todisappears. determine total tin content. Strip terne coating with reagent 17.3 Perchloric Acid—The handling and storage of perchlo- grade hydrobromic acid (48 %) containing 10 mL/L of a 10 %ric acid should be conducted in accordance with the precau- antimony trichloride/hydrochloric acid solution. (Dissolve 10 gtions given in Practices E 50, Safety Precautions. antimony trichloride in 100 mL of concentrated hydrochloric acid, sp gr 1.19.) Reduce with aluminum wire and titrate with18. Procedure for Stripping potassium iodate solution. Strip alloy layer in a 1:3 nitric acid solution, reduce with aluminum wire and titrate in potassium 18.1 After cleaning in accordance with 6.3, weigh the test iodate solution. Total tin content is equal to the tin in thespecimen to the nearest 0.001 g. Place the specimen in a coating plus the tin in the alloy layer.suitable stripping dish. Add 40 mL of stripping solution 19.3.3 Calibration and Standardization:(Warning, see 17.2), and immediately begin policing both 19.3.3.1 Prepare tin standards ranging from 0 to 200 mg/Lsides of the specimen. After 30 s, remove the specimen using by transferring the required amounts of standard, 1000 mg/LTFE-fluorocarbon forceps and place it in a filter funnel that has tin solution (from 16.11) to 100-mL volumetric flasks (0, 1.0,been inserted into a 200-mL volumetric flask. Rinse the 2.0, 5.0, 10.0, 15.0, and 20.0 mL). Add 20 mL of the stock leadspecimen with HCl (1+1), catching and saving all rinsings in solution (from 16.4) to each flask, dilute to volume with HClthe volumetric flask. Inspect the surface of the specimen for (1+1), and mix.unremoved coating by using a “scratch” test. (Scratching the 19.3.3.2 The exact operation of different instruments varies;specimen surface with a fingernail leaves a noticeable metallic hence no attempt is made here to describe in detail the steps forscratch if any coating is left on the surface. The base metal will putting the instrument into operation. However, the followingnot leave such a mark.) If the scratch test reveals residual parameters have been found suitable for some types of instru-coating, repeat the stripping (using original solution) and ments.rinsing steps until the surface is free of coating. Rinse the Lamp current, mA 10stripped test specimen with water, dry, and reweigh. The loss in Main air supply, psi 40weight represents the weight of coating together with iron Air flow, standard ft3/h 10dissolved from the steel sheet. Main acetylene supply, psi 10 Acetylene flow, standard ft3/h approximately 8 Main nitrous oxide (N2O) supply, psi 4019. Chemical Analysis Nitrous oxide (N2O) flow, standard ft3/h approximately 10 Slit band width, A ˚ 4 19.1 Transfer the sample stripping solution to the 200-mL Wavelength, A˚ 2863 (0 to 200 mg/L)flask that contains the rinsings and dilute to volume with HCl Consult manufacturer’s manual for the equivalent operating(1+1). parameters for the instrument in use. 19.2 Determination of Iron—Transfer a 50-mL aliquot into 19.3.3.3 Atomize the standards and record the instrumenta 250-mL beaker. Add 10 mL of HClO4 and take to fumes on readings expressed in absorbance units. Aspirate water be-a hot plate (Warning, see 17.3). Cool solution, then add 100 tween each standard.mL of water, 5 mL of HCl, and heat to boiling. Immediately 19.3.3.4 Prepare a calibration curve by plotting on linearreduce the iron with addition of the SnCl2 reducing solution. graph paper the absorbance versus standard concentration forAdd 3 drops in excess after the disappearance of the ferric iron each standard.color. Cool and dilute to about 175 mL with water. Add to the 19.3.4 Procedure:solution, all at once, 10 mL of the saturated HgCl2 solution. 19.3.4.1 Atomize the sample stripping solution under theMix gently by stirring the solution. Let stand for 3 to 5 min. conditions in 19.3.3.Add 20 mL of the sulfuric-phosphoric acid mixture and 5 to 6 19.3.4.2 Determine concentration of the stripped sampledrops of the sodium diphenylamine sulfonate indicator solu- solution using the calibration curve. Determine concentrationtion. Titrate with the standard K2Cr2O7 solution to a purple end in milligrams per litre.point. Calculate the grams of iron in the stripping solution asfollows: 20. Calculation Iron, g 5 4AB 20.1 Weight of Coating—Calculate the weight of coating in ounces per square foot of sheet as follows:where: Weight of coating, oz/ft 2 5 A 2 BA = K 2Cr2O7 standard solution required to titrate to a purple end point, mL andB = iron equivalent of the K2Cr2O7 solution, kg/L. where: A = loss in weight of specimen, g, and 19.3 Determination of Tin: 5
  • 6. A 309 – 01 7B = grams of iron stripped from the test specimen (from 21. Precision and Bias 19.2), when a specimen of 5.08 in.2 (3277 mm2) in 21.1 Due to the limited number of laboratories participating area is used. For specimens of other sizes, a suitable in the cooperative testing of the tin analysis procedure, a correction factor must be applied. precision statement conforming to the requirements of Prac- 20.2 Percentage of Tin in Coating—Calculate the tin con- tices E 173 cannot be furnished. Comparison of the percentagetent as follows: tin found by the three cooperating laboratories (Table 1) with Tin, % 5 mg/L tin/50 @A 2 B# the known tin value in the samples indicates an error of approximately 0.2 to 0.3 % tin. Therefore, this procedure can be expected to be within 3 % of the expected tin value.where:A − B = weight of coating, oz/ft 2, when a specimen of 5.08 in.2 (3277 mm2) in area is used. For speci- 22. Keywords mens of other sizes, a suitable correction factor 22.1 coating composition; coating weight; metallic coat- must be applied. ings; steel sheet—terne coated; terne coating 7 Supporting data are available from ASTM Headquarters. Request RR: A05- 1001. ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, at the address shown below. This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the above address or at 610-832-9585 (phone), 610-832-9555 (fax), or service@astm.org (e-mail); or through the ASTM website (www.astm.org). 6